1. Field of the Invention
The invention relates generally to an improved planing hull design for a power boat and, more specifically, to a high speed power boat having an improved hull design shape including a tunnel section that is positioned center and aft of an at least one transverse step.
2. Discussion of the Related Art
High speed powerboats utilize various design features for speed and stability. Powerboats utilize planing to reduce displacement and the resulting friction/wave resistance resulting in an increase in speed. Offshore powerboats require additional features to ensure stability while running at high speeds over a rough water surface.
Planing refers to the hydrodynamic process whereas, on increasing speed, the boat is lifted up relative to the water surface by dynamic pressure acting over the surface of the boat hull bottom. This dynamic pressure is a function of increasing boat speed. At rest, the boat is supported (floats) by pressure provided by hydrostatic forces, resulting in the boat being positioned deeper in the water thereby displacing a larger water volume than when planing.
Conflicting conditions of operation exist with the typical planning craft:                1. Displacement (low speed) mode, requiring relatively large displaced volume and larger wetted surface area, and        2. Planing (high speed) mode, requiring relatively small displacement and smaller wetted surface area.        
The conflict is that, in order to have the area needed for displacement operation, excessive area and its accompanying excessive drag tend to occur in high speed planing operation.
Modern planing craft resolve this conflict to some degree by the use of lifting strakes, stepped hulls, chines, and/or combinations thereof. All three of the hull form modifications shown function to separate the flow in steady planing (as well as in seaway slamming) to produce a smaller area for reduced planing resistance (and impact acceleration).
Another known design for increasing speed of a powerboat is the incorporation of transverse ventilation steps. When a boat is traveling at high speeds, suction is created between the contacting surface area of the hull and the surface of the water. These ventilation steps provide a channel for releasing the created suction. By reducing the suction, the ventilation steps introduce another issue, as the directional stability is compromised.
What is desired is a boat hull comprising features that reduce the amount of drag, while maintaining or increasing directional stability and control. The present invention over-comes the prior art deficiencies, providing a novel design that increases directional stability while maintaining features which relieve hull suction which are not apparent, obvious, or suggested, either directly or indirectly by the known art.